1. Field of the Invention
The present invention relates to an image processing technique.
2. Description of the Related Art
In recent years, a liquid-crystal display device has been used as a television receiver or a display device for a PC. Such a liquid-crystal display device has been widely used because it can be formed thin and saves space and power. In such a liquid-crystal display device, however, the response time for motion video is long.
As a driving method for a liquid-crystal display device to improve the response time, there has been provided a method of comparing image data to be displayed next with previous image data, and performing overdrive in accordance with the comparison result (Japanese Patent Laid-Open No. 11-126050).
As a method of improving motion blurring due to the display characteristics of a liquid-crystal display device, there has been proposed a method of driving the display device by doubling the frame frequency of an input image signal, and by inserting a black image or an intermediate image (Japanese Patent Laid-Open No. 2002-351382).
Furthermore, the following technique has been proposed (Japanese Patent Laid-Open No. 2006-184896). One frame is divided into a plurality of subframes by raising the frame frequency of an input image signal. High-frequency components of an image signal used to display an image in at least one predetermined subframe of the plurality of subframes are decreased as compared with image signals used to display images in other subframes.
If the change amount of the high-frequency components is large, however, a value exceeding a display range may be generated, thereby disturbing the display image or displaying an extra video. If this problem is addressed by decreasing the high-frequency components, the motion blurring improvement effect decreases (deteriorates).